Today we visit the Weddell Sea, which lies to the east of the Antarctic Peninsula. Like the rest of the Southern Ocean, the body of water that surrounds Antarctica, it is home to diverse ecosystems that are filled with unique and astonishing wildlife. And like oceans everywhere, the impacts of climate change are becoming more apparent.
As the world warms, its waters are warming, too. Increased temperatures have already led to changes in ocean life. For example, on the other side of the Peninsula, king crabs have invaded an area previously considered far too cold for their survival. The impact of the arrival of these predators, for the first time in millions of years, could be catastrophic for the surrounding ecosystem, which has evolved exotic and unique life forms that have no defenses against crabs.
Unfortunately, scientists are observing not only changes to the oceans’ temperature but also to its chemistry. The Weddell Sea — and the rest of the Southern Ocean — is experiencing what scientists call ocean acidification. Currently, about a quarter of the carbon dioxide released each year by human activities is absorbed by the world’s oceans. The Southern Ocean alone absorbs more than 40% of that due to the frigid temperatures of its waters. As the concentration of carbon dioxide increases, the water becomes more acidic.
As one scientist described it to me, ocean acidification is the “osteoporosis” of the world’s oceans. As the ocean acidifies, the exoskeletons of marine animals become brittle and frail, just as osteoporosis weakens the bones of humans. Acidification can also affect the nervous systems, blood circulation, and breathing of fish and other animals in the sea. In other parts of the world, acidification may cause tissue damage in economically important species of fish, threaten the survival of rare or endangered shellfish, and reduce the number of species in coral reefs. If left unchecked, this fundamental alteration to ocean chemistry has the potential to threaten the livelihood and food security of millions, if not billions, of people worldwide.
And, what does this mean for us? About 1 billion people in the world rely on fish and shellfish as their primary source of dietary protein. By one estimate, the effect of acidification on mollusks alone (animals such as oysters and clams) could cost the world tens of billions of dollars by the end of the century. Some researchers have called acidification “one of the most critical anthropogenic threats to marine life.”
The climate crisis is a problem of multiple dimensions. Rising ocean temperatures alone have the potential to disrupt the web of life in the ocean. Acidifying oceans, a result of the same carbon dioxide pollution that is warming our planet, are magnifying the problem even further.